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Effects of Corona Discharge from the Grounding Tip on Charge Evolution of Wall Bushing

IEEE Transactions on power Delivery 2025年第3期40卷 1682-1693页

作者： Bai, Zheng Zhou, Yuanxiang Zhang, Yunxiao Huang, Xin Xie, Xiongjie Liu, Taiwei Tsinghua University State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Beijing100084 China Electric Power Research Institute State Key Laboratory of Power Grid Environmental Protection Wuhan430204 China

Manufacturers consider that the grounding tip near the wall bushing flange is a potentially important factor in several sheath perforation accidents. Taking a ±100 kV true type SF6 gas-insulated bushing as a typical wall bushing, this paper tests the impact of the nearby grounding tip on the charge accumulation. Based on the experiment results, we propose the three-dimensional nonlinear conduction model to unravel the charge accumulation process and the three-dimensional corona ion migration model to clarify the corona process. It is concluded that the consumption of gas ions leads to the nonlinear charge relaxation process. When the corona of grounding tip incepts, numerous ions are generated, forming an "overcharge" phenomenon. The electric field at the insulator-sheds interface and the SF6-insulator interface increases compared to the normal condition, with non-uniform distribution along the circumferential direction. Material inhomogeneity amplifies electric field distortion and creates insulation weaknesses, making insulation aging more likely and potentially leading to a slowly developing electrical tree breakdown process. The length of the needle tip affects the duration of the corona effect;an excessively long needle tip can cause a sustained corona discharge. This research provides a foundation for bushing accidents analysis and operation reliability improvement. © 1986-2012 IEEE.

关键词： Bushings

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A novel single-phase Zr-Hf-Ta-O ceramic with high fracture toughness for thermal barrier coatings

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Ceramics International 2025年第12期51卷 15603-15612页

作者： Cheng, Chunyu Chen, Long Luo, Junhui Zhou, Liucheng Li, Guifang Yang, Li Zhou, Yichun Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for Aerospace School of Advanced Materials and Nanotechnology Xidian University Xi'an710126 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Shaanxi Xi'an710038 China

Hf6Ta2O17 has attracted great interest in thermal barrier coatings (TBCs) in the field of aero-engine due to the excellent ultra-high temperature thermal stability and low thermal conductivity. However, its lower fracture toughness than that of 7–8 wt % yttria-stabilized zirconia (YSZ) limited the application. Here, ZrO2 was doped into Hf6Ta2O17 to form the Zr-Hf-Ta-O ceramic by solid-phase reaction method to improve its fracture toughness. The effect of the doped Zr on the Hf6Ta2O17 structure and mechanical properties of Zr-Hf-Ta-O ceramics were studied by experiment and first-principle simulation. The results showed that the prepared Zr-Hf-Ta-O ceramic exhibited the single orthorhombic phase due to the Zr atom diffusing into the Hf6Ta2O17 structure and substituting the Hf atom at high temperatures. The substituted Hf atom might fall on an interstitial site. By increasing the content of ZrO2, the gradient rise of lattice parameters was realized and the doped Hf6Ta2O17 structure grew along the a-axis. Besides, the introduction of ZrO2 significantly enhanced the hardness and fracture toughness of the Hf6Ta2O17 ceramic. The most significant improvement was observed for the Zr-Hf-Ta-O ceramic with the molar ratio of HfO2, Ta2O5, and ZrO2 of 6:1:3 (2.41 ± 0.05 MPa m1/2). The introduced Zr atom strengthens the covalency of its adjacent Ta-O and Hf-O bonds in the Zr-Hf-Ta-O structure, thus enhancing its mechanical properties. Through apprehending the role of the doped Zr on the structure and properties of Hf6Ta2O17, designed elements might be added to the ceramic structure to further change its mechanical properties. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Thermal barrier coatings

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Verification and Testing of Emergency Stability Control for Micro-Grid in Industrial Park

Verification and Testing of Emergency Stability Control for ...

引用

2025 International Conference on Electrical Automation and Artificial Intelligence, ICEAAI 2025

作者： Yang, Zaixin Han, Tao Qu, Yannan Taopu, Yedong Institute of Relay Protection Inner Mongolia Electric Power Science & Research Institute Inner Mongolia Key Laboratory of Smart Grid of New-type Power System Hohhot China

ISBN: (纸本)9798331506797

With the development and transformation of industrial micro-grid, analyzing the emergency stability control of micro-grid when a fault occurs and the section is disconnected is of significant importance. In this paper, the industrial power grid characteristics are analyzed and the mathematical model of comprehensive loads are established. An emergency stability controller with voltage control and frequency control functions is proposed and the block of controller is designed by the programming language DSL. A micro-grid in industrial park based on RTDS is used for semi physical simulation testing of emergency stability control strategy. Simulation of under-frequency reverse power show that the correctness and effectiveness of the emergency stability control strategy. © 2025 IEEE.

关键词： DSL emergency stability control micro-grid RTDS

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PLLA-PEG/mPEG Copolymer with Improved Hydrophilicity, Crystallinity, and Biocompatibility: An In-Depth Study on the Crystallization Kinetics

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ACS Applied Materials and Interfaces 2025年第20期17卷 30067-30080页

作者： Lian, Ruixian Zhou, Dong Xiao, Lan Rodrigues, João Sheng, Ruilong Bai, Zhishan Li, Yulin Liu, Changsheng The Key Laboratory for Ultrafine Materials of Ministry of Education Engineering Research Centre for Biomedical Materials of Ministry of Education Frontiers Science Center for Materiobiology and Dynamic Chemistry School of Materials Science and Engineering East China University of Science and Technology Shanghai200237 China Wenzhou Key Laboratory of Tissue Regeneration Medical Materials Wenzhou Institute of Shanghai University Wenzhou325000 China State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process School of Mechanical and Power Engineering East China University of Science and Technology Shanghai200237 China School of Medicine and Dentistry Griffith University QLD4222 Australia CQM-Centro de Química da Madeira MMRG Universidade da Madeira Campus da Penteada Madeira Funchal9000-390 Portugal

Poly(lactic acid) (PLA) possesses excellent biocompatibility and biodegradability for the construction of biomaterials. However, its limited crystallinity largely restricts practical application. In this study, four poly(l-lactic acid) (PLLA) copolymers were synthesized by incorporating two different molecular weights of PEG/mPEG (1K and 2K) chains with l-lactide via ring-opening polymerization (ROP). The impact of PEG/mPEG chains on the hydrophilicity and mechanical properties of the resulting copolymers, their crystallization kinetics, and activation energy was also examined. The results demonstrate that introducing PEG/mPEG chains could significantly improve the hydrophilicity, crystallinity, and crystallization rate and reduce the maximum crystallization temperature of the copolymer materials. Among the PLLA copolymers, PLLA-mPEG (2K) exhibits the most remarkable improvements in polymer crystallinity, crystallization rate, and reduction of the maximum crystallization temperature. The advancements in copolymer material properties were anticipated to significantly expand the potential applications for PLLA-based polymer materials, which also greatly improved the applicability as sustainable and controllable biopolymer materials. © 2025 American Chemical Society.

关键词： Biocompatibility

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Verification and Testing of Emergency Stability Control for Micro-Grid in Industrial Park

Verification and Testing of Emergency Stability Control for ...

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Electrical Automation and Artificial Intelligence (ICEAAI), International Conference on

作者： Zaixin Yang Tao Han Yannan Qu Yedong Taopu Inner Mongolia Key Laboratory of Smart Grid of New-type Power System Institute of Relay Protection Inner Mongolia Electric Power Science & Research Institute Hohhot China

ISBN: (数字)9798331506797

ISBN: (纸本)9798331506803

关键词： Computer languages power system stability Control systems Stability analysis power grids Mathematical models DSL Voltage control Frequency control Testing

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Research on applicability of containment test data for HPR1000 based on phenomena scaling

International Journal of Advanced Nuclear Reactor Design and...

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International Journal of Advanced Nuclear Reactor Design and Technology 2025年第2期7卷 120-127页

作者： Liu Yusheng Qiao Xuedong Tan Sichao Jing Jianping Wang Ting Zhu Yuanbing State Environmental Protection Key Laboratory of Nuclear and Radiation Safety Regulatory Simulation and Validation Nuclear and Radiation Safety Center MEE Beijing 100086 China Guangdong Provincial Key Laboratory of Nuclear Power Safety Shenzhen 518026 China Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin 150001 China China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen 518026 China

The volume of the nuclear power plant containment is huge, making it difficult to conduct equal-scale or large-scale thermal-hydraulic tests. Currently the test data mainly come from small-scale tests. To address the applicability of small-scale containment test data in validation process of the containment performance analysis code, the analysis method for applicability of experimental data is proposed and developed on the basis of similarity analysis of the pressure response process in the containment. The applicability study of the test data, which are produced by some scaled containment facilities such as the HDR, Battelle and CVTR, is carried out in combination with the test parameters. The applicability of each test case isobtained respectively when they are applied to validate the containment code in case of the Large Break Loss of Coolant Accident (LBLOCA) and Main Steam Line Break Accident (MSLB) of HPR1000 nuclear power plant. The results show that the similarity criteria for pressure response process and key phenomena within the containment vessel under accident conditions can be employed to analyze the applicability of different containment tests to specified power plant. The test dataoriginating fromHDR ISP-16 and HDR ISP-23can represent the pressure transient process, results of coupling phenomena such as mass and energy release at the break, condensation near the containment shell and internals, within the HPR1000 containment in case of LBLOCA or MSLB. The distortion is either within the acceptable range or conservative for design limits of containment pressure, so that the small-scale containment test data could be suitable for verification and validation of the HPR1000 containment thermal hydraulic response analysis code.

关键词： Containment Similarity analysis Validation Safety analysis Pressure response HPR1000

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Experimental study of multi-mechanism flow instabilities in low-pressure natural circulation systems for pool type heating reactor

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Annals of Nuclear Energy 2025年 221卷

作者： Zhang, Yankun Feng, Shou Liu, Yusheng Sun, Rulei Tian, Ruifeng Tan, Sichao Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Engineering Harbin Engineering University Harbin150001 China Key Laboratory of Nuclear Safety and Advanced Nuclear Energy Technology Ministry of Industry and Information Technology Engineering Harbin Engineering University Harbin150001 China Nuclear and Radiation Safety Centre Ministry of Environmental Protection of the People's Republic of China China

In the two-phase thermal system, flow drift or self-sustaining oscillation is easy to occur, resulting in mechanical vibration or thermal stress damage, disturbing system control and even inducing boiling crisis in advance. The deep pool heating reactor is a complex low-pressure natural circulation system under the condition of loss of flow accident. Therefore, it is necessary to study the flow instability under such condition. In this paper, a series of transient performance data including inlet flow rate are obtained by building a simulation test bench. It is found that the oscillation characteristics of inlet flow change obviously with the small heating power increase (5 kW) when it is more than 120 kW. By distinguishing the causes of different flow oscillations, we found that there are many different flow instability mechanisms in this system, including pressure drop oscillations, geysering, flashing induced instability and density-wave oscillations. Among them, the longest pressure drop oscillations cycle reaches 449 s, and the relative amplitude reaches 33.9 %. The coupled density-wave oscillations phenomenon triggered by the lowest point of pressure drop oscillations causes the flow stagnation. Through the windowed fast Fourier transform and empirical mode decomposition method, we quantitatively and qualitatively analyze the effects of the interaction between different types of flow instability. we found that it is precisely because of such effects of the various parts above-mentioned that the strong nonlinear characteristics are caused. The experimental data show that the maximum heating power of the reactor during the accident should not exceed 120 kW (corresponding to 60.74 % of the design operating power). This study believes that adjusting the internal characteristic curve of the system will significantly improve the stability of such system. © 2025

关键词： Machine vibrations

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Time series online prediction algorithm based on least squares support vector machine

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Journal of Central South University of Technology 2007年第3期14卷 442-446页

作者：吴琼刘文颖杨以涵 Key Laboratory of Power System Protection and Dynamic Security Monitory and Control of Ministry of Education North China Electric Power University

Deficiencies of applying the traditional least squares support vector machine （LS-SVM） to time series online prediction were specified. According to the kernel function matrix＇s property and using the recursive calculation of block matrix, a new time series online prediction algorithm based on improved LS-SVM was proposed. The historical training results were fully utilized and the computing speed of LS-SVM was enhanced. Then, the improved algorithm was applied to timc series online prediction. Based on the operational data provided by the Northwest power Grid of China, the method was used in the transient stability prediction of electric power system. The results show that, compared with the calculation time of the traditional LS-SVM（75 1 600 ms）, that of the proposed method in different time windows is 40-60 ms, proposed method is above 0.8. So the improved method is online prediction. and the prediction accuracy（normalized root mean squared error） of the better than the traditional LS-SVM and more suitable for time series online prediction.

关键词： time series prediction machine learning support vector machine statistical learning theory

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Microstructural evolution mechanism of aluminide coating on the inner hollow of superalloy blades during service in a real gas turbine

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Journal of Materials Science and Technology 2025年 239卷 55-69页

作者： Liu, Junkai Li, Qian Xie, Yuqi Luo, Junhui Zhang, Changxing Wang, Weiwei Cao, Ke Liang, Xiaoqing Yang, Li Zhou, Yichun School of Advanced Materials and Nanotechnology Xidian University Xi'an710126 China Guangzhou Institute of Technology Xidian University Guangzhou510555 China Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for Aerospace Xidian University Xi'an710126 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Xi'an710038 China

The microstructural evolution of an aluminide coating, prepared by chemical vapor deposition on the inner surface of a superalloy blade, was comprehensively investigated during service in a real gas turbine. The as-deposited coating exhibited a dual-layer structure: the outer layer predominantly composed of β and γ' phases, and the inner layer consisting mainly of β, γ', and σ phases. A secondary reaction zone (SRZ), enriched with needle-like σ phases, developed inside the superalloy substrate beneath the coating. Despite the blade not being enriched with refractory elements, three types of topologically close-packed (TCP) phases—σ, μ, and P—precipitated. During the aluminizing process, the needle-like σ phase formed first, followed by the transformation of σ to P and μ phases, with P and μ nucleating within the σ phase. The transformation coordinate was proposed and simulated through density functional theory (DFT) calculations. Coherent relations were observed between different TCP phases and between TCP phases and superalloy substrate. The aluminide coating exhibited varying oxidation behaviors due to its microstructural diversity. Interfacial oxidation dominated the oxidation process, attributed to the enrichment of Ti in the inner coating layer and the co-oxidation of Ti and Al. The γ → γ' transformation within the SRZ led to the shrinkage of the original γ phase into line-like structures. Additionally, the aluminizing and homogenization processes were simulated using the DICTRA code, with results that align well with experimental observations. © 2025

关键词： Thermooxidation

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Enhancing Corrosion Resistance of Copper for C4F7N Based Eco-Friendly Gas-Insulated Equipment

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High Voltage 2025年

作者： Xiao, Song Xia, Haoran Li, Zhanyuan Wang, Yifan Tang, Ju Zhang, Xiaoxing Li, Yi State Key Laboratory of Power Grid Environmental Protection School of Electrical Engineering and Automation Wuhan University Hubei China Baoding Baoling Transformer Company Ltd. Baoding China Key Laboratory for High-Efficiency Utilization of Solar Energy and Operation Control of Energy Storage System School of Electrical and Electronic Engineering Hubei University of Technology Wuhan China

Perfluoroisobutyronitrile (C4F7N) is recognised as the next-generation dielectric medium for eco-friendly gas-insulated equipment (GIE). However, there is gas metal incompatibility in strong electromagnetic environments and environmentally friendly insulating gas atmospheres that endangers the operational safety and service life of GIE. Here, a solvent-induced grain boundary reconstruction method was proposed to prepare corrosion-resistant copper rapidly. Accordingly, the partial discharge-induced gas–metal interaction was simulated and the corrosion resistance properties of copper were evaluated. Additionally, the gas–solid interaction mechanism was investigated and the improvement mechanism of the proposed method on the stability of the gas–solid interface was discussed. Related results provide a reference for the development and application reliability of C4F7N-based eco-friendly GIE. © 2025 The Author(s). High Voltage published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology and China Electric power Research Institute.

关键词： Oxidation resistance

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